SQL Group By Clause

What is Group By clause ?

In this Article Group by clause use in Select query in Sql Server when you fetch data with collection on basis particular unique field then use Group by Clause. Group by clause with where condition and order by clause.

The GROUP BY statement is used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns.

Syntex

SELECT ColumnName FROM TableName WHERE condition GROUP BY ColumnName ORDER BY ColumnName

Example

SELECT COUNT(Id) as Counts,City FROM Tbl_Employee GROUP BY City
Create table Tbl_Employee with some field and group by city.
if you run query with GROUP BY Clause then you find group wise city records.
In case if you use Group By Clause then always use aggregate functions.If you not use aggregate function then face error.
You can see in example

Select All records in image- image
Group by clause on city -

The HAVING Clause

The HAVING clause use in SQL because the WHERE keyword could not be used with aggregate functions.

Syntex

SELECT ColumnName, Aggregate Function(ColumnName) FROM TableName WHERE ColumnName operator value GROUP BY ColumnName HAVING Aggregate Function(ColumnName) operator value

SELECT COUNT(Salary) AS Counts,Salary,City FROM Tbl_Employee GROUP BY City ,Salary HAVING Salary > 25000
Note - You should aware having condition apply then this field must be in aggregate function and group by clause